The present invention relates to an occupant position detection system for detecting an occupant position in a seat of a vehicle.
A vehicle may contain a device for detecting a position of an occupant who sits in a seat of a vehicle for purposes of mitigating occupant injury. In order to sense the distance to the occupant from an instrument panel of the vehicle as an occupant position, a position sensor is used which incorporates either an infrared beam or an ultrasonic beam as the sensing element which transmits sensing beams such as either the infrared beam or the ultrasonic beams to the occupant from a distance sensor located on the instrument panel.
FIGS. 8A to 8C show an example wherein a distance sensor 103 is mounted on an instrument panel 101 of a vehicle to sense the distance between the instrument panel 101 and an occupant 102.
In such a sensing system, the distance sensor 103 first transmits one or more sensing beams to the occupant 102. The sensing beams are reflected off the occupant 102 and, so, a sensor section of the distance sensor 103 enables to sense the reflected sensor beams. When this occurs, the time interval between the sensing beams transmitted from the distance sensor 103 to the occupant 102 and the sensing beams reflected off the distance sensor 103 from the occupant 102 is measured, enabling to sense the distance to the occupant 102 from the instrument panel 101 on the basis of the sensed time interval and the transmission velocity of the sensing beams.
In such a distance sensor 103, when there is the presence of an object 105 such as a book or hand baggage, held by an occupant, between the instrument panel and the occupant as viewed in FIG. 8A, the distance sensor 103 is caused to measure the distance between the instrument panel 101 and the object 105 as a false distance between the instrument panel 101 and the occupant.
It is therefore an object of the present invention to provide an occupant position detection system which enables to correctly detect an occupant position regardless of a condition of a seat back of a vehicle seat, an occupant posture or an object held by the occupant in close proximity to an instrument panel.
According to one aspect of the present invention, there is provided an occupant position detection system which includes distance sensor means located on a seat back of a seat of a vehicle, angle sensor means for sensing an inclined angle of the seat back, and sliding displacement sensor means for sensing a sliding displacement value of the seat in the fore and aft directions.
The occupant position is detected by the distance sensor means, the angle sensor means and the sliding displacement sensor means.
With such an occupant position detection system, the occupant position is detected by the distance sensed by the distance sensor means mounted on the seat back, the inclined angle and the sliding displacement value of the seat in fore and aft direction and, therefore, it is possible to correctly detect the distance to the instrument panel from the occupant even when the obstacle such as the book or the hand baggage exists between the instrument panel and the occupant.
According to another aspect of the present invention, there is provided an occupant position detection system which includes first distance sensor means located on a seat back of a seat of a vehicle, second distance sensor means located on an instrument panel of the vehicle, angle sensor means for sensing an inclined angle of the seat back, and sliding displacement sensor means for sensing a sliding displacement value of the seat in fore and aft directions. A first distance is computed responsive to signals output from the first distance sensor means, the angle sensor means and the sliding displacement sensor means, and an occupant position is detected by the first distance and a second distance sensed by the second distance sensor means.
With such an occupant position detection system, the occupant position is detected on the basis of the first distance sensed from the rear side of the occupant and the second distance sensed from the front side of the occupant and, thus, it is possible to correctly detect the distance to the instrument panel from the occupant regardless of the conditions of the seat, the occupant posture or the object held by the occupant in close proximity to the instrument panel.
According to a further aspect of the present invention, there is provided an occupant position detection system wherein the first distance corresponds to a sensed distance to the occupant from the instrument panel which sensed distance is computed on the basis of a distance sensed from a rear side of the occupant, and wherein the first and second distances are compared to detect the occupant position.
With such an occupant position detection system, the first distance computed on the basis of the value detected from the rear side of the occupant is utilized as the distance between the instrument panel and the occupant and, accordingly, it is possible to directly compare the first and second distances. With such a comparison of the distances of two kinds, it is possible to correctly detect the distance to the instrument panel from the occupant in a more reliable manner.